(using kubernetes v1.15.7 in minikube and matching client version and minikube 1.9.0)

If I kubectl apply a secret like this:

apiVersion: v1
data:
  MY_KEY: dmFsdWUK
  MY_SECRET: c3VwZXJzZWNyZXQK
kind: Secret
metadata:
  name: my-secret
type: Opaque

then subsequently kubectl apply a secret removing the MY_SECRET field, like this:

apiVersion: v1
data:
  MY_KEY: dmFsdWUK
kind: Secret
metadata:
  name: my-secret
type: Opaque

The data field in the result is what I expect when I kubectl get the secret:

data:
  MY_KEY: dmFsdWUK

However, if I do the same thing using stringData instead for the first kubectl apply, it does not remove the missing key on the second one:

First kubectl apply:

apiVersion: v1
stringData:
  MY_KEY: value
  MY_SECRET: supersecret
kind: Secret
metadata:
  name: my-secret
type: Opaque

Second kubectl apply (stays the same, except replacing MY_KEY's value with b2hubyEK to show the configuration DID change)

apiVersion: v1
data:
  MY_KEY: b2hubyEK
kind: Secret
metadata:
  name: my-secret
type: Opaque

kubectl get result after applying the second case:

data:
  MY_KEY: b2hubyEK
  MY_SECRET: c3VwZXJzZWNyZXQ=

The field also does not get removed if the second case uses stringData instead. So it seems that once stringData is used once, it's impossible to remove a field without deleting the secret. Is this a bug? Or should I be doing something differently when using stringData?